The present invention relates to communications systems in general. More specifically, the invention relates to techniques to efficiently deliver interactive program guide (IPG) in a server-centric system.
Over the past few years, the television industry has seen a transformation in a variety of techniques by which its programming is distributed to consumers. Cable television systems are doubling or even tripling system bandwidth with the migration to hybrid fiber coax (HFC) cable plant. Customers unwilling to subscribe to local cable systems have switched in high numbers to direct broadcast satellite (DBS) systems. And, a variety of other approaches have been attempted focusing primarily on high bandwidth digital technologies, intelligent two way set top terminals, or other methods of trying to offer service differentiated from standard cable and over the air broadcast systems.
With this increase in bandwidth, the number of programming choices has also increased. Leveraging off the availability of more intelligent set top terminals, several companies such as Starsight Telecast Inc. and TV Guide, Inc. have developed elaborate systems for providing an interactive listing of a vast array of channel offerings, expanded textual information about individual programs, and the ability to look forward to plan television viewing as much as several weeks in advance and the option of automatically programming a VCR to record a future broadcast of a television program.
Unfortunately, the existing program guides have several drawbacks. They tend to require a significant amount of memory, some of them needing upwards of one megabyte of memory at the set top terminal (STT). They are very slow to acquire their current database of programming information when they are turned on for the first time or are subsequently restarted (e.g., a large database may be downloaded to a STT using only a vertical blanking interval (VBI) data insertion technique). Disadvantageously, such slow database acquisition may result in out of date database information or, in the case of a pay per view (PPV) or video on demand (VOD) system, limited scheduling flexibility for the information provider. Furthermore, the user interface of existing program guides do not usually look like a typical television control interface; rather the user interface looks like a 1980""s style computer display (i.e., blocky, ill-formed text and/or graphics).
Therefore, it is desirable to provide an interactive program guide in a manner tending to reduce the above-described problem. With the increase in the quantity of programming and rich multimedia content of a program guide, it is a challenge to deliver program guide audiovisual data to viewers in an efficient and effective manner. A large amount of resources (e.g., bandwidth) would normally be needed to continually transmit, for example, two weeks of programming for 200 channels. Therefore, efficient and effective techniques to provide interactive program guide to a large number of viewers are highly desirable.
In this invention, the drawbacks cited in the previous art are overcome by a server-centric encoding system that processes the guide data and associated audiovisual content at a central location (e.g., a head-end) and delivering the display ready guide pages to receiving terminals. The invention provides various techniques to encode, deliver, and decode interactive program guide (IPG). These techniques exploit known characteristics of IPG pages and further employ picture-based or slice-based recombination techniques to minimize the transmission and processing of redundant information. Each IPG page can be decomposed into a guide portion that is specific to each IPG page and a background portion that is common to all IPG pages. The background portion can be further decomposed into a video portion that is time-varying and other portions that may be static or slowly moving over time (i.e., slow motion). These various portions of the IPG pages can be efficiently processed and delivered in the manners described below.
In the picture-based recombinant methods described below and in the aforementioned U.S. patent application Ser. No. 09/466,990, the guide and video portions for each IPG page were processed (processing including picture-based splicing) as picture by picture, where the guide portion was composed with one frame of motion video, intra-coded, and sent to the decoder as I-picture. A number of I-pictures were sent for a number of IPG pages. At a terminal, one of the I-pictures (i.e., the selected guide page) was then re-combined with predicted pictures to form a complete GOP. The recombination was performed at the xe2x80x9cpicturexe2x80x9d level, which is simple and easy for the decoder in comparison to the xe2x80x9cslicexe2x80x9d level recombination. In this picture-based recombination technique, each I-picture contains data for both the guide and video portions and occupies more bandwidth than necessary as the intra-coded motion video portion of each IPG page was repeatedly sent along with each I-picture that carries different guide page data.
In the slice-based recombination methods also described below and in the aforementioned U.S. patent application Ser. No. 09/466,990, the guide portion and each video portion were processed slice-by-slice (e.g., with each slice defined as one or more rows of macroblocks in a picture). With slice-based recombination, the redundancy of the picture-based recombination process was significantly reduced by sending the video portion slices in a separate PID once, a nd recombining the video portion slices with different guide page slices to regenerate different IPG pages. The guide page slices for each guide page were also sent as a separate PID . However, the slice-based recombination algorithm requires more encoder and decoder resources to handle slice-level processing, including slice-by-slice splicing of guide and video (and background) portions.
In the present invention, a unique approach is provided that reduces the processing overhead but still uses low bandwidth for delivery of guide content. The approach uses picture-based recombination, with the pictures including only selected slices. In MPEG, a picture does not need to include all the slices of a frame, and even if picture-based processing is applied only the portion(s) of the frame defined by the slices are processed and updated on the screen. Note that the invention is not tied to any particular standard, including MPEG, and the techniques described herein can be applied within proprietary solutions and other standards. The invention introduces a new paradigm of encoding algorithms that takes advantage of the fact that even though picture-by-picture encoding/decoding is performed, in the temporal domain, only the selected slices for certain regions (e.g., the guide region) are updated as required or requested. In other words, slices temporally persist on the screen until overwritten by new information.